Borehole inclinometer



April 26, 1960 R, A, B050 ETAL 2,933,820

r BOREHOLE INCLINOMETER Filed Nov. 23, 1956 v 2 Sheets- Sheet 1 INVENToRs R. S. HOCH R. A. BOBO A TTORNEYS R. A. BOBO ETAL BOREHOLE INCLINOMEITER April 26, 1960 2 Sheets-Sheet 2 Filed NOV. 23, 1956 INVENTORS R.S. HOCH R.A. BOBO BY www@ ATTORNEYS BOREHOLE INCLINOMETER Roy A. Bobo and Robert S. Hoch, Houston, Tex., as-

signors to Phillips Petroleum Company, a corporation of Delaware Application November 23, 1956, Serial No. 623,977

9 Claims. (Cl. 33-205) This invention relates to the measurement of inclinations of boreholes during drilling operations.

ln oilproducing operations, it is common practice to drill boreholes by means of a rotary drill string which has a drill bit attached to the lower end thereof. Adrilling lluid is circulated downwardly through the drill string and upwardly in the annular region between the drill string and the wall of the borehole. This fluid serves primarily to clean the hole beneath the bit, and to remove cuttings from the wells. During such drilling operations, it is important to be able to determine the inclination of the borehole at all times because boreholes commonly deviate from a vertical direction due to several facto'rs which include: excess weight on the drill bit, a

atent C" too rapid drilling rate, ilexure of the drill pipe caused by excessive weight, poor alignment in the starting hole, bent drill pipe, unsymmetrical bits, ,and changes in, character of the formations through which the borehole passes. The present practice when drilling with mud is to drop a survey instrument to the bottom just prior to pulling of a bit, wait a specified time for the device to record, and remove it with the bit. If a measurement of the hole deviation is desired oftener than each trip, the survey instrument is lowered to the bottom through the drillrstring on a wire line and removed after a speciedtime by. retrieving hole with mud prior to trips. Modern drilling practices,

with longer bit footages and faster penetration rates and with attendant hole deviation, make mandatory the Vobtaining of crooked hole indications oftener than once per trip of the drill string. Securing such information by the wire line method is both time consuming. and .hazardous because the drill string must remain in the hole without rotation and without fluid circulation while the survey is being taken. 5 Y

In accordance with the present invention, thereis provided an improved borehole inclinometer which is capable of being operated in conjunction with a drill string so that measurements can be made whenever desired merely by stopping the circulation ofidrilling fluid. Thus, each time a new length of drill pipe is added to the string,"a measurement is made of the borehole inclination. This measurement is made by the apparatus of this invention eject- I ing a vreadily identifiable substance into the drilling iluid which is then carried to the surfacev by continued circulation of the drilling Huid. A small colored ball is employed to advantage as the identifiable substance. The

apparatus isprovidedwith a plurality of balls in dilerentA colors so that the ball ejected has a colorv which is representative of the deviation of the borehole from a vertical direction. The apparatus of this invention can readily be attached to conventional drilling equipment andoper- 2,933,826 Patented Apr. 26, 1960 icc ates without the necessity of removing` the drill string from the borehole at the time the measurement is made.

Accordingly, it is an object of this invention to provide hole inclinometer which can be employed with conventional drilling equipment.

Other objects, advantages and features of this invention should become apparent from the following detailed description which is taken in conjunction with the accompanying drawing in which:

Figure l is a schematic representation of a rotary drilling rig having the borehole inclinometer of this invention attached thereto.

Figure 2 is a detailed View, shown partially in section, of the lower portion of the inclinometer of this invention.

Figure 3 is a detailed view, shown partially in section, of the upper portion of the inclinometer of this invention.

Figure 4 is a schematic circuit diagram of the electrical components of the inclinometer of Figures 2 and 3.

Figure 5 shows a modilied form of the ejection apparatus.

Referring now to the drawing in detail and to Figure l in particular, there is shown a conventional rotary drilling rig. A casing 10 isv anchored in the upper region of a borehole 11. A drill string 12 extends downwardly through casing 10 into the hole being drilled. The inclinometer 13 of this invention -is attached to the lower end of drill string 12. A drill bit 14 is attached to the lower end of inclinometer 13.` The upper end of drill string 12 is rotated by a suitable source of power, not shown, which is connected to drill string 12 through bevel gears 15. Drilling fluid is passed from a pit 16 through a conduit 17 by means of a pump 18 to enter a swivel 19 at the top of drill string 12. This drilling fluid circulates downwardly through drill string 12 and inclinometer 13 and passes outwardly into borehole 11 through bit 14. The borehole cuttings are carried by the drilling uid upwardly through the annular space surrounding drill string 12. The drilling fluid is removed at the surface through a conduit 21 which discharges over a shale shaker 22 into pit 16. The inclinometer of this invention selectively ejects identifiable substances, such as small colored balls, which pass upwardly through the borehole and are recovered at the surface on shaker 22 or at any other suitable place. The path taken by one of these balls is illustrated in Figure 1 by the dotted circles.

inclinometer 13 is illustrated in detail in Figures 2 and 3. The instrument comprises an elongated sleeve 29 which is attached at its upper end to drill string 12 by means of threads 30. The drill bit 14 is attached to the lower'end of sleeve 29 by threads 31. An elongated cylindrical casing 32 is positioned centrally within sleeve 29 and rests ona shoulder 33 of sleeve 29 near the lower end thereof. A battery case 34 tits on the top of casing 32 and has a cap 39 mounted thereon. A spider 36 is positioned immediately above cap 39 and is locked into position by being rotated under a plurality of lugs 37 which are attached to the inner wall of sleeve 29. A set screw 38 extends through spider 36 and engages cap 3Q so as to secure casing 32 rigidly within sleeve 29.

A housing 40 is fitted into sleeve 29 at a region beneath casing 32. A bellows 41 is disposed within housing 40 and is attached at its upper end to the lower end of the central portion of casing 32. A plurality of openings 42 extend from the exterior of bellows 41 to a region outside sleeve 29. These openings apply the pressure of the drilling fluid outside inclinometer 13 to the interior of housing 49 so as to tend to compress bellows 41. A passage -44 extends from a region within bellows 41 upwardly through casing 32 to a chamber 46. An ad` justable needle valve 45 is formed in passage 44 to control the opening thereof. A piston 47 is disposed within casing 32 above chamber 46, and a compression spring 48 is positioned in chamber 46 to tend to force piston 47 upwardly. A shaft 49 is vattached to piston 47 and carries a support member 53v at the upper end thereof. Support member 53 is disposed within a housing 52 in casing 32. One or more passages 50 extend from the region S1 above piston 47 to the interior of housing 52. An electrical contact disk 55 and a plurality of annular contact members 56, '7, 58, and 59 are carried by support member 53. These contact members are electrically insulated from one another by means of spacing members 60, 61, 62, and 63. A pendulum 66 is freely suspended so as to assume a vertical position at all times. A contact member 68 depends from pendulum 66 and is urged downwardly by a compression spring 69.

A plug 71 is fitted within casing 32 on top of housing 52 and is retained in position by means of a sleeve 72. Plug 7l is provided with a passage 75 into which is disposed a movable piston 76. Piston 76 is provided with an orilice 77. An electrical contact member 78 is attached to the top of plug 71. so as to engage piston 76 when the piston moves upwardly through passage 75. A second bellows 80 is attached to the top of plug 71 so that the interior thereof communicates with the upper end of passage'75. A filling plug 82 is attached to bellows 8) so that the interior of this bellows, the interior of housing 52, chambers 51 and 46, and the interior of bellows 41 can be filled with a hydraulic electrically insulating fluid, such as oil. Casing 32 is provided with openings 81 adjacent bellows 80 so that the drilling fluid in the annular chamber between casing 32 and sleeve `29 exerts a pressure on bellows 80 which tends to collapse the bellows.

A iirst solenoid 84 is flexibly attached to a support bracket 83 which in turn is attached by a scre w 85L vto casing 32. The upper vportion of bracket 83 is provided with a hollow cylindrical extension 86 which protrudes through an opening 87 in casing 32. YA lhollow cylindrical member 88 is attached exterior of casing 3,2 above cylindrical member 86,. The two cylindricalmembers have a common passage which is filled with a plurality of balls 89. A weight 90 rests on the top of balls 89 so as to tend to push the balls downwardly. A perforated plug, not shown, can be inserted in the top of cylinder 88 if desired to prevent the weight and balls from accidentally being ejected upwardly. A rocker arm 93 which has a` slotted end portion is pivotally attached to an extension 92 of a plunger 91 of magnetic material within solenoid 84. The slotted end of rocker arm 93 receives the lower ball 89 in cylinder 86. Rocker arm 93 is also pivotally attached to member 86 at a point designated as 98. A compression spring 97 exerts a force downwardly on pivotal connection 95. When solenoid 84 is energized, plunger 91 moves upwardly to occupy a region at the center of the solenoid and in vso doing lifts the lower end of rocker arm 93. This pivots rocker arm 93 about its connection 98 to compress spring 97 and in so doing forces the lowermost ball 89 outwardly into the annular passage between casing 32.1and sleeve 29. When solenoid is deenergize'd, rocker` arm returns to the position illustrated. The pivotalmounting of solenoid 84 on support 83 permits this movement of rocker arm 93.

The illustrated ejection apparatus thus employs a push 4 type electromagnet. It should be evident that a pull" arrangement can be provided by locating a pull type solenoid 84', see Figure 5, above arm 93 and by locating a tension spring 97 below arm 93.

Four additional solenoids 84a, 84h, 84C, and 84d are similarly mounted within casing 32 above solenoid 84. These solenoids are providedwith respective rocker arms 93a, 93b, 93e, and 93d which are adapted to 'eject respective balls 89a, 89b, 89e, and 89d. The live sets of balls preferably are dilferent colors so that they can readily be identied.. These balls are ejected into the drilling mud in the annular passage between casing 32 and sleeve 29. The balls are subsequently carried by the drilling fluid downwardly through one of the passages 35, out through thedrillfbit 14,V and then to the surface where they are recovered and identified on shale shaker 22.

The electrical circuit associated with the mechanical components of the inclinometer is shown schematically in Figure 4. A battery 188 is mounted within chamber 10% in case 34 of Figure 2. One terminal of this battery is grounded by being connected to metallic case 34. The second terminal of battery 100 is connected by suitable leads to first end terminals of solenoids 84, 84a, 841;, 84e, and 84d. The second terminals of these solenoids are connected to respective electrical contacts 55, 56, 57, 58, and 59 which are carried by support member 53. Contact 78 is connected to metallic pendulum 66 which is in electrical contact with member 68. Piston 76 is grounded by being in electrical contact with plug 71 which in turn is connected to case 34 through casing 32. The electrical leads have been omitted from Figures 2 and 3 in order to simplify the drawing. It should be evident, however, that the leads can be contained in suitable conduits mounted either internally or externally of casing 32.

The operation of the inclinometer of this invention should now become apparent. During drilling operations, when the drilling fluid is being circulated, the fluid pressure inside the drill string is generally several hundred pounds greater than the pressure in the annular region surrounding the drill string, depending on the size of the bit no'zzles. The drilling fluid pressure within the drill string is applied through openings 81 to bellows 80. This tendsy to compress bellows which forces support member 53 to the lower position illustrated in Figure 2. The' pressure of the drilling tluid outside the drill string is applied through openings 42 to bellows 41. This pressure tends to compress bellows 41 and to move support member 53 upwardly. Since the pressure on bellows 80 is greater than the pressure on bellows 41, support member 53 is retained in the lower position. be observed that pendulum 66 is out of engagement with the electrical contacts carried by sup'port member 53 at .this time. When the drill string rotation is stopped and the circulation of drilling fluid is terminated, the pressures on bellows 80 and bellows 81 tend to equalize. This results in compression spring 48 pushing piston 47, shaft 49 anjd support member 53 upwardly. If inclinometer 13 is' in a vertical positiommember 68 engages contact 55. v Spring-69 insures that contact is completed. This completes an electrical circuit between the two members fsofthat pendulum 66 is in electrical contact with member 55. .At the same time, the increased pressure within housing 52.pushes piston 76 upwardly into engagementfwith contact 78. y This completes the electrical circuit between battery and solenoid 84 so that plunger 91 is moved upwardly to rotate yrocker arm 93 and expelaball 89. If the borehole is slightly inclined at'l the timey the circulationof drilling uid is terminated, member* 68 moves into engagement with contactv 56. This eiiergi'zesv solenoid 84d to eject a ball 89a. Similarly, the solenoid .energized and the ball ejected is It should 5 66. The assembly can be 56, 57, 58, and 59 represent inclinations of two degrees, three degrees, four degrees, five degrees, and six degrees from a vertical position, respectively, for example.

After a ball has been ejected, piston 76 moves slowly downwardly under the force of gravity so as to break contact with member 78. Orifice 77 enables the hydraulic fluid to ow through the piston to permit this downward movement. This breaks the electrical circuit and prevents further drain on battery 100. Adjustable needle valve 45 permits the rate of fluid flow, through orifice 44 to be adjusted so as to regulate the upward travel time of support member 53. It is desired that this travel time be sufficiently long that the `assembly is at rest before a measurement is made.

In normal operation, the inclinometer is actuated each time circulation of drilling uid is terminated. This normally yoccurs each time an additional section of drill pipe is added to the drill string. However, a measurement can be made at any time merely by terminating the circulation of drilling fluid. After a ball has been ejected, it is desirable to circulate the drilling fluid for a brief period prior to the time that rotation of the drill string is again commenced. This enables the ball to move downwardly through the assembly and out through the openings in drill bit 14. It should be evident however that the assembly can be modified so that the balls are ejected directly into the annular space between the drill string and the wall of the borehole to avoid any possible damage to the balls by the drill bit. The balls preferably are constructed of a plastic or rubber material of low cost. These balls are formed of different colored materials so that each color is representative of a particular inclinatron.

While the invention has been described in conjunction with the injection of balls, it should be evident that other types of identifiable substances can be employed if desired. For example, characteristic liquids or gases can be ejected and subsequently identified at the surface.

From the foregoing description, it should be evident that there is provided in accordance with this invention an improved borehole inclinometer. The device can readily be attached to a conventional drill string and can be operated without removing the drill string from the well. Furthermore, the instrument can be operated a number of times with a single loading of balls. The supply of balls can be replenished whenever the drill string is pulled from the well to replace a drill bit.

While the invention has been described in conjunction with a present preferred embodiment, it should be evident that it is not limited thereto.

What is claimed is:

1. A borehole inclinometer comprising a housing adapted to be secured to a drill string, a pendulum freely mounted within said housing to assume a vertical position when said housing is lowered into a borehole, a

designed so that contacts 55,"

support member positioned within said housing adjacent y into engagement with one another so that said supportr member and said pendulum are in engagement with one another except when the drilling uid pressure internally of said drill string adjacent said housing exceeds the drilling fiuid pressure externally of said drill string adjacent said housing by a predetermined amount, and means responsive to said pendulum engaging said target means to eject an identiable substance into the drilling uid adjacent said housing.

2. A borehole inclinometer comprising a housing adapted to be secured to a drill string, a pendulum freely mounted within said housing to assume a vertical position when said housing is lowered into a borehole, a support member positioned within said housing adjacent said pendulum, a plurality of target means carried by said support member in spaced relationship with one another so that said pendulum engages one of said target means when said pendulum and said support member are closely spaced to one another, the target means being engaged by said pendulum being representative of the amount said housing is inclined from a vertical direction, means responsive to the drilling fiuid pressure within said drill string to tend to separate said support member from said pendulum, means responsive to the drilling fiuid pressure externally of said drill string to tend to move said support member and said pendulum into engagement with one another, means urging said support member and said pendulum into engagement with one another so that said support member and said pendulum are in engagement with one another except when the drilling fluid pressure internally of said drill string adjacent said housing exceeds the drilling fiuid pressure externally of said drill string adjacent said housing by a predetermined amount, a plurality of sources of identifiable substances, the substances being distinguishable, one from the other, and means responsive to said pendulum engaging said target means to eject said substances into the drilling fluid adja'-' cent said housing, the particular substance ejected being representative of the target engaged.

3. The apparatus of claim 2 wherein said sources of identifiable substances comprise containers filled with solid members of different colors, the colors of said members being representative of the individual container.

4. A borehole inclinometer comprising a housing ladapted to be secured to a drill string, a pendulum suspended within said housing to assume a vertical position when said housing is lowered into a borehole, a support member disposed within said housing adjacent said pendulum, a target means carried by said support member so as to be engaged by said pendulum when said support member and said pendulum are closely spaced to one another and said housing is inclined from a vertical direction a predetermined amount, a first bellows carried by said housing and communicating externally with the drilling fluid inside the drill string, the interior of said first bellows communicating with the interior of said housing on the side of said support member adjacent said pendulum, means urging said support member into engagement with said pendulum, a second bellows carried by said housing and communicating externally with the drilling fluid outside the drill string, the interior of said second bellows communicating with the interior of said housing on the side of said support member away from said pendulum, a hydraulic fiuid within said housing and said bellows so that said support member and said pendulum are in engagement with one another except when the drilling Huid pressure internally of said drill string adjacent said housing exceeds the drilling fluid pressure externally of said drill string adjacent said housing by a predetermined amount, and means responsive to said pendulum engaging said target means to eject an identifiable substance into the drilling fluid adjacent said housing.

5. The apparatus of claim 4 wherein said means to eject an identifiable substance comprises a container having the identifiable substance therein, electrically operated means to open said container when energized, a current source, and circuit means to connect said source to said electrically operated means, said circuit means including said pendulum and said target means so that said circuit means is completed when said pendulum engages said target means.

6. The apparatus of claim 5 further comprising means plunger moves to the second end of said passage, said` circuit means including said contact and said plunger s'ol as t0 be completed only when said plunger engages said contact. l

7. A borehole inclinometer comprising a housing adapted to be secured to a drill string, a pendulum freely mounted within 4said housing to assume a vertical position when said housing is lowered in to a borehole, a sup'- port member positioned within said housing adjacent said pendulum, a plurality of target means carried by said support member inspaced relationship with one another so that said pendulum engages one of said target means when said pendulum and said support member are closely spaced to one another, the target means engaged by said pendulum being representative of the amount said housing is inclined from a verticalvdirection, a plurality of sources of identifiable substances, the substances being distinguishable, one from the other, means urging said support member and said pendulum into engagement with one another, means to retain said support member outof engagement with said pendulum when the drilling fluid pressure 'within said drill string exceeds the drilling uid pressure outside said drill string by a predeternl inel` amount, and means responsive to saidY pendulum engaging said target means to eject -said substancesvinto the drill-"l ing uid adjacentv said'housing, the particular' st ibshtanc'sv ejected being representative ofthe target engaged.'

8. The apparatus of claim 7 wherein said targetmeans comprise a central disk of electrically conductive mate? rial and a'plurality of concentric rings of electrically conductive materials, and wherein said means to eject'comprises a plurality of containers for said substances, electrically operated means to open said containers when energized, a current source, and circuit means to connect said source to said electrically operated means through said pendulum and a respective one of said target means formed by said disk and said rings.

9. The apparatus of claim 4 further comprising a valve between one of said bellows and said housing to restrict the ow of hydraulic uid from one bellows to the 'other' a predetermined amount to delay actuation of the inclinometer by a predetermined time interval.

References Cited in the le of this patent UNITED STATES PATENTS 2,232,360 Barnett Feb. 18, 1941 2,303,360 Irwin et al. Dec. l, 1942 2,658,284 Arps `Nov. 10, 1953 2,700,897 Arps Feb. 1, 1955 2,755,432 Arps et al'. 2 f July 17, 1956 

